What two rivers served as boundaries between the U.S. and Mexico?
Michael Gray
Updated on May 10, 2026
Texas used the Adams-Onís as a boundary line to the U.S., but decided to set the Rio Grande (called the Río Bravo del Norte in Mexico) as its boundary line to Mexico.
Which river is the boundary between the US and Mexico?
The Rio Grande is the fifth longest river in the United States and among the top twenty in the world. It extends from the San Juan Mountains of Colorado to the Gulf of Mexico (1,901 miles) and forms a 1,255 mile segment of the border between the United States and Mexico.What 2 Rivers did Mexico and the US disagree on as the border between them?
Key Points
- Conflict with Mexico began when the United States annexed Texas as a state in 1845.
- Mexico claimed that the new border between Texas and Mexico was the Nueces River, while the United States contested the border was the Rio Grande.
What are the 2 rivers that form parts of the United States border?
Sharing the Rio GrandeThe US and Mexico share the waters of the Rio Grande, which is defined through a series of agreements between the two countries.